The present invention relates to a flat chamber for filling with fluid media which is defined by two essentially parallel limiting plates and a circumferential bead of a cured, impermeable adhesive between the plates which bonds the plates to one another.
Chambers of this type, whose plate separation can be, for example, from 0.1 to 1 mm and in which the area extent of the plates can be between fractions of a cm2 and several dm2, are used as functional containers for liquids which change their properties, in particular their optical properties, such as colour, absorption capacity, optical activity, etc., under the action of external influences, such as electric or magnetic fields, temperature, radiation, etc. Correspondingly, at least one of the limiting plates is designed to be optically transparent if the desired effect is observed in reflection. If the desired effect is observed by means of back-illumination or the like, both parallel limiting plates consist of a transparent material. Examples of suitable transparent materials are glass plates, polycarbonate sheets and the like.
Particular interest has recently been paid to electrochromic displays in the form of mirrors or display elements. In electrochromic displays, a colour change of the electrochromic liquid takes place under the action of the electric field. Displays are therefore constructed in the form of flat chambers, in which the parallel limiting plates are made a transparent material with a light-transparent, electrically conductive coating, in particular an indium-tin oxide (ITO) coating, which is in contact with the electrochromic liquid. In the case of electrochromic mirrors, one of the coatings is in the form of a non-transparent, reflective, metallic layer.
Displays or mirrors of this type are disclosed in principle in U.S. Pat. No. 3,451,741, EP-A 240 226 and WO 94/23333. Preferred electrochromic liquids are described in the German patent applications 196 05 448, 196 05 441, 196 21 865 and 196 31 729.
In order to keep an electrochromic mirror or an electrochromic display functional in the long term, it is necessary to keep the electrochromic liquid away from contact with atmospheric oxygen and other compounds which are reactive with the electrochromically active substances and to prevent evaporation of constituents of the electrochromic liquid, in particular solvents, i.e. it is necessary to encapsulate the electrochromic liquid securely in the chamber. In addition, the chamber must be filled with the electrochromic liquid without gas bubbles, since gas bubbles restrict the use of such displays and mirrors. A further problem is contact of the electrochromic liquid with uncured components of the epoxy resin adhesive usually employed. The unreacted components of the adhesive react with the electrochromically active substance and possibly further components of the electrochromic liquid.
The multifarious problems associated with the production of the flat chamber and its filling have hitherto only been solved inadequately. Regarding the prior art, reference is made to U.S. Pat. No. 5,233,461, whose introduction cites a number of prior-art proposals for solving the problems and which itself discloses a further proposal.
The present invention relates to a flat chamber for filling with fluid media of the type mentioned at the outset, with the characterizing feature that at least one capillary is provided which runs parallel to the limiting plates, passes through the adhesive bead and is bonded thereto.
The external diameter of the capillary is smaller than the separation of the plates. Capillaries of this type can easily be produced from quartz and are commercially available in standardized form for use in high-pressure liquid chromatography. For example, for flat chambers having a plate separation of 0.2 mm, quartz capillaries from Seitz Chromatografie Produkte GmbH, Weiterstadt, Germany, with the Article Nos. SC 100 170 and SC 075 150 are suitable. These have external diameters of 0.17 mm and 0.15 mm respectively and internal diameters of 0.1 mm and 0.075 mm respectively.